PELAGIC PLANT LIFE 



327 



resembling one another and all belonging to the same genus, 

 namely, Dinophysis. The commonest of these, D. acuta (see Dinophyi 

 Fig, 231), has a small tongue-shaped mobile cell without particu- 

 larly well-defined suspension -organs. Its ring- furrow and 

 protecting borders are situated at 

 the forepart of the cell, and its 

 sides are flattened to such an 

 extent that the ventral furrow is 

 on quite a sharp edge, where it is 

 guarded by two membrane-cur- 

 tains. The cell is formed by 

 division, which takes place per- 

 pendicularly to the ring- furrow. 

 Within the cell are several brown 

 chromatophores, showing that 

 Dinophysis is one of the peri- 

 dineae that assimilates carbonic 

 acid. 



In warmer waters this funda- 



FiG. 2-^1.— Dinophysis acuta. 



From the west coast of Norway (-?--)• 



(Jorgensen. ) 



Fig. 232. 



a, Amphisolenia globosa ; 



b, Amphisolenia tenella, n.sp. {^\^ 



mental type shows strange variations. Amphisolenia (see Fig. Amphisolenia. 



232) has its w^hole cell drawn out to a hair, the ring-furrow is 



situated right in front on a little head, and the ventral furrow 



is on a narrow neck with slightly developed membrane-curtains 



like a kind of collar. The cell widens out slightly like a spindle 



in the middle, and posteriorly ends in a globular knob by way 



of balance, or in two or three ramifications. Triposolenia (see Triposoienia. 



Fig. 233) has a similar anterior structure, but the middle part is 



